diff options
authorGilad Ben-Yossef <gilad@benyossef.com>2012-03-28 14:42:44 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-28 17:14:35 -0700
commita8364d5555b2030d093cde0f07951628e55454e1 (patch)
parentsmp: add func to IPI cpus based on parameter func (diff)
slub: only IPI CPUs that have per cpu obj to flush
flush_all() is called for each kmem_cache_destroy(). So every cache being destroyed dynamically ends up sending an IPI to each CPU in the system, regardless if the cache has ever been used there. For example, if you close the Infinband ipath driver char device file, the close file ops calls kmem_cache_destroy(). So running some infiniband config tool on one a single CPU dedicated to system tasks might interrupt the rest of the 127 CPUs dedicated to some CPU intensive or latency sensitive task. I suspect there is a good chance that every line in the output of "git grep kmem_cache_destroy linux/ | grep '\->'" has a similar scenario. This patch attempts to rectify this issue by sending an IPI to flush the per cpu objects back to the free lists only to CPUs that seem to have such objects. The check which CPU to IPI is racy but we don't care since asking a CPU without per cpu objects to flush does no damage and as far as I can tell the flush_all by itself is racy against allocs on remote CPUs anyway, so if you required the flush_all to be determinstic, you had to arrange for locking regardless. Without this patch the following artificial test case: $ cd /sys/kernel/slab $ for DIR in *; do cat $DIR/alloc_calls > /dev/null; done produces 166 IPIs on an cpuset isolated CPU. With it it produces none. The code path of memory allocation failure for CPUMASK_OFFSTACK=y config was tested using fault injection framework. Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Pekka Enberg <penberg@kernel.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Sasha Levin <levinsasha928@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Avi Kivity <avi@redhat.com> Cc: Michal Nazarewicz <mina86@mina86.org> Cc: Kosaki Motohiro <kosaki.motohiro@gmail.com> Cc: Milton Miller <miltonm@bga.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 files changed, 9 insertions, 1 deletions
diff --git a/mm/slub.c b/mm/slub.c
index f4a6229848fd..dcbb1926cb7f 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2028,9 +2028,17 @@ static void flush_cpu_slab(void *d)
__flush_cpu_slab(s, smp_processor_id());
+static bool has_cpu_slab(int cpu, void *info)
+ struct kmem_cache *s = info;
+ struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
+ return !!(c->page);
static void flush_all(struct kmem_cache *s)
- on_each_cpu(flush_cpu_slab, s, 1);
+ on_each_cpu_cond(has_cpu_slab, flush_cpu_slab, s, 1, GFP_ATOMIC);